Typically, trailers used to transport boats, recreational homes and other such objects weighing sometimes up to 10,000 pounds are equipped with a surge brake system. A surge brake system utilizes a spring biased piston actuator that moves relative to the trailer when the towing vehicle decelerates to force brake fluid into the wheel brakes, and thus slowing the trailer. However, when the towing vehicle and trailer are motionless or stopped, the surge brake system is not actuated and the trailer's brakes are not engaged.
Hence, a parked trailer with a surge brake system must be immobilized against rolling down a sloped surface by keeping the trailer hitched to the towing vehicle or by blocking the trailer's wheels. But when the trailer greatly outweighs the towing vehicle, it may drag the hitched towing vehicle down a sloped surface. Blocking the trailer's tires may not always be effective due to the type of block used or the surface upon which the trailer rests.